High-voltage fuses having zig-zagshaped fuse link



E LINK May 9, 1967 P, c. JACOBS, JR

HIGH-VOLTAGE FUSES HAVING ZIG-ZAGSHAPED FUS Filed `Feb. 7, 1966 FIGB INVENToR PHILIP C. JACOBS JR.

BY RAM/W, ATToRm-:Y

United States Patent C) 3,319,029 HIGH-VOLTAGE FUSES HAVING ZIG-ZAG- SHAPED FUSE LINK Philip C. Jacobs, Jr., 53 Walden St., Newtonville, Mass. 02160 Filed Feb. 7, 1966, Ser. No. 525,587 3 Claims. (Cl. 200-120) This invention relates to high-voltage fuses, i.e. fuses designed for circuit voltages in excess of 600 volts and up to many kilovolts.

If fuses for relatively high circuit voltages are intended to carry relatively large currents, it is necessary, or desira'ble, to p-rovide such fuses with fusible elements in form of ribbons rather than in form of wires.

It is one object of this invention to provide improved high-voltage fuses having ribbon fuse links.

In fuses having ribbon fuse links the latter are generally bent in a certain fashion tending to arrange relatively lfong fuse links between terminal caps, or other terminal elements, having a predetermined relatively limited spacing, less than the length of the fuse links when not bent, but fully stretched out. Another object of bending fuse links extending between a pair of terminal elements or terminal caps is to preclude the occurrence of more or less severe stresses therein which may result from manufacturing tolerances and other variations of the distance between the ends of the fuse links.

It is another object of this inventio-n to provide highvoltage fuses having bent fuse links to meet the aforementioned requirements, and which meet simultaneously other requirements which are, lor may be, vital to the proper operation of highavoltage fuses.

One of these additional requirements is to ibe very current-limiting and, in order to achieve this end, to minimize the fusing i2-t values of ribbon fuse links. Another of these additional requirements is to adapt ribbon fuse links to accepting the kind of arc-voltage control means disclosed and claimed in U.S. Patent 2,964,- 604 to Philip C. Jacobs, Jr., et al., Current-Limiting Fuses Having Compound Arc-Voltage Generating Means, issued Dec. 13, 1960i.

It is, therefore, another object of this invention to provide high-voltage fuses having ribbon fuse links that are longer, when fully stretched out, than the spacing |between the terminal caps, or other terminal elements of the fuses, that are free from dangerous stresses, that include serially related points of drastically reduced cross-section minimizingl fusing i2t values without rendering the fuse links excessively fragile and that generate relatively stable rather than rapidly decaying arc voltages incident to interruption of faulted circuits by the fuses.

For a better understanding of the invention reference may be had to the accompanying drawings wherein:

FIG. l is substantially a vertical section of a highvoltage fuse embodying this invention, some of the structure being shown in elevation rather than in section;

FIG. 2 is a portion of a cross-section of the embodiment of FIG. 1 taken along 2 2 of FIG. l;

FIG. 3 is a detail of the structure of FIG. l drawn on a larger scale than FIG. l;

FIG. 4 is an isometric view of a modification of a portion of the fuse link structure of FIG. l; and

FIG. 5 is an isometric view of .a portion of the fuse link structure of FIG. 1.

Referring now to the drawings and more particularly to FIGS. l, 2, 3 and 5 thereof, tubular casing 1 of insulating material is closed on the axially outer ends thereof by a pair of terminal elements in the form of caps 2. Terminal plates 3 are arranged inside of casing 1 immediately adjacent and parallel to the end surfaces of caps 2. Terminal plates 3 are conductively intercon- 3,319,029 Patented May 9, 1967 nected by a plurality of ribbon fuse links 4. A column or spacer of insulating material 5 extends .along the axis of casing 1 and maintains terminal plates 3 properly spaced, `as indicated in FIG. l. Terminal plates 3 are provided with radially extending slots 3a receiving the end portions of ribbon fuse links 4. The latter are provided with connector tabs on the axially outer ends thereof which are bent into the planes of terminal plates 3 and spot-Welded to the outer surfaces thereof as indicated at 4' in FIG. 2. Thus terminal plates 3, ribbon fuse links 4 and spacer or column 5 form a self-sustained sub-assembly unit.

Fuse links 4 are bent to zigezag shape, their total length before being so Ibent substantially exceeding the distance between terminal plates 3. Fuse links 4 include serially related points of maximal cross-sectional area where they are bent to zig-zag shape, and further include points of reduced cross-sectional area alternating with the aforementioned points of maximal cross-sectional area. Since the point of reduced cross-sectional area are spaced from the points where the fuse links 4 are bent to zig-zag shape, the former points are virtually free from any stresses. Hence their cross-sectional area can be drastically reduced to minimize the fusing iz't and the letthrough currents of the fuse.

In the ribbon fuse link structure shown in FIGS. l and S the points of reduced cross-sectional area are formed by circular perforations.

In the ribbon fuse link structure shown in FIG. 4 the points of reduced cross-sectional area are formed by lateral substantially V-shaped incisions. Alternating incisions define points 4a, 4b of different cross-sectional area. The cross-sectional area of points 4a may be less than that of points 4b. As a result, points 4a and points 4b will fuse sequentially incident to loccurrence of major fault current, resulting in a relatively limited initial peak of the arc voltage and in a relatively stable arc voltage. Points 4a of reduced cross-section are, or may be, sand- Wiched between a pair of plates of a melamine-liberglass-cloth laminate held in position by suitable fasteners such as, for instance, a pair of eyelets projecting through each pair of sandwiching plates. Plates 6` stilfen the fuse links 4 at the points where their cross-sectional area and their mechanical strength or dimensional stability is smallest. They segregate the pulverulent arc-quenching filler 7 inside of casing 1 from the breaks formed :at points of reduced cross-sectional area 4a incident to 'occurrence of major fault currents. As a result, the arc voltage of the arcs formed at points 4a is relatively small, but more stable than if points 4a were directly immersed in the pulverulent arc-quenching filler 7. The presence of plates 6 further tends to preclude the formation of fulgurites shunting the breaks formed at points 4a as long as such fulgurites are hot.

Upon completion of sub-assembly unit 3, 4, 5 the latter is inserted into casing 1 and the lower cap is mounted on the latter. Caps 2 Iare provided with one or more holes 2a for establishing one or more solder joints 8 between terminal plates 3 and terminal caps 2. The upper terminal plate 3 is provided with a circular hole 3b arranged in registry with a circular hole in the upper cap 2 and the filler 7, e.g. quartz sand, is lled through lboth holes into casing 1. Thereafter the hole in upper cap 2 is closed :by a disc 9 which is soldered in position to close the fuse structure permanently.

It will be apparent from the foregoing that fuses embodying this invention include substantially zig-zag shaped fuse link means inside the casing thereof conductively interconnecting a pair of terminal elements and submersed in :an arc-quenching filler. The aforementioned fuse link means include a plurality of serially related at sections defining planes enclosing predetermined obtuse angles. Any increment of the area of any of said plurality of sections encloscs said predetermined angle with any increment of the area of an adjacent of said plurality of sections. Contiguous pairs of said sections are bounded by section-limiting straight edges at the loci of intersection of said planes. Each of said plurality of sections has its largest cross-sectional area .at the pair of said section-limiting edges thereof. Each of said plurality of sections has a point `of minimum cross-sectional area situated between `said section-limiting edges thereof.

While, in accordance with the patent statutes, I have disclosed the details of a preferred embodiment of my invention, it is to be Iunderstood that many of these details are merely illustrative and variations in their precise form will be possible -or necessary, depending upon the particular nature of application.

I desire, therefore, that my invention be limited only to the extent set forth in the appended claims and by the prior art.

I claim asmy invention:

1. A high-voltage fuse comprising in combination:

(a) a tubular casing of an electric insulating material;

(b) terminal elements closing the ends of said casing;

(c) a pulverulent arc-quenching filler inside said casing; and

(d) substantially zig-zag shaped ribbon fuse link means inside said casing conductively interconnecting said pair of terminal elements and submersed in said arc-quenching ller, said fuse link means including a plurality of serially related at sections dening planes enclosing predetermined obtuse angles, any

increment of the area of any of said plurality of sections enclosing said predetermined obtuse angle with any increment of the area of an .adjacent of said plurality f sections, contiguous pairs of said `sections being Ibounded by section-limiting edges at the loci of intersection of said planes, each of said plurality of sections having its largest cross-sectional area at the pair of said section-limiting edges thereof, and each of said plurality of sections having a point of minimum cross-sectional area situated between said section-limiting edges thereof.

2. A high-voltage fuse as specified in claim 1 wherein said plurality of points of reduced cross-sectional area are formed :by a plurality of at perforated fuse link sections and wherein a portion of said plurality of at perforated fuse link sections is sandwiched between pairs of insulating plates.

3. A high voltage fuse including:

(a) a tubular casing of an electric insulating material;

(b) terminal elements closing the ends of said casing;

(c) a pulverulent arc-quenching `filler inside said cas- (d) ribbon fuse link means inside said casing embedded in said filler conductively interconnecting said pair of terminal elements, said fuse link means having a plurality of serially related points of reduced crosssectional area alternating with serially related points of relatively large cross-sectional area, said plurality of points of reduced cross-sectional area being formed by a plurality of substantially flat perforated fuse link sections and said fuse link means being bent at said plurality of points of relatively large crosssectional area intermediate said plurality of points of reduced cross-sectional area substantially to zigzag shape; and

(e) a plurality of pairs of insulating plates sandwiching a portion of said plurality of points of reduced crosssectional area formed by said plurality of substantially at perforated fuse link Sections.

References Cited bythe Examiner UNITED STATES PATENTS 2,157,906 5/1939` Lohausen 200-135 3,134,874 5/1964 Cameron 200-135 3,183,327 5/1965 Kozacka 200--120 3,213,242 10/1965 Cameron 200--120 BERNARD A. GILHEANY, Primary Examiner. H. B. GILSON, Assistant Examiner.

REEXAMINATION CERTIFICATE (474th) Jacobs, J r.

HIGH-VOLTAGE FUSES HAVING ZIG-ZAG-SHAPED FUSE LINK inventor; Philip C. Jacobs, Jr., Newtonvme,

Mass.

[73] Assignee: Gould, Inc., Rolling Meadows, Ill.

Reexamination Request:

No. 90/O0O,303, Dec. 3, 1982 Reexamination Certificate for:

Patent No.: 3,319,029

Issued: May 9, 1967 Appl. No.: 525,587

Filed: Feb. 7, 1966 [51] Int. CL4 H01H 85/04 [52] U.S. Cl. 337/276; 337/290 [58] Field of Search 337/159, 158, 295, 236,

[56] References Cited U.S. PATENT DOCUMENTS 3,134,874 5/1964 Cameron 337/158 3,213,242 10/1965 Cameron 337/159 [11] B1 3,319,029 [45] Certificate Issued k Api.j1,1986

3,374,328 3/1968 Cameron 337/236 4 Primary Examiner-Harold v Broome EXEMPLARY CLAIM [1. A high-voltage fuse comprising-in combination:

(a) a tubular casing of an electric insulating material;

(b) terminal elements closing the ends of said casing;

(c) a pulverulent arc-quenching filler inside said casing;

and

(d) substantially zig-zag shaped ribbon fuse link means inside said casing conductively interconnecting said pair of terminal elements and submersed in said arcquenching filler, said fuse link means including a plurality of serially related flat sections defining planes enclosing predetermined obtuse angles, any increment of the area of any of said plurality of sections enclosing said predetermined obtuse angle with any increment of the area of an adjacent of said plurality of sections, contiguous pairs of said sections being bounded by section-limiting edges at the loci of intersection of said planes, each of said plurality of sections having its largest cross-sectional area at the pair of said section-limiting edges thereof, and each of said plurality of sections having a point of minimum cross-sectional area situated between said sectionlimiting edges thereof] i THE PATENT IS HEREBY AMENDED AS r i B1 3,319,029 y y REEX'AMINATIQN CERTIFICATE As A RESULT oF REXAMIATIQ, ffr HAS ISSUED UNDER 3s U.s.c. 307 BEEN DETERMINED THAT:

5 Claims 1-3 are cancelled.

INDICATEDBELOW l f *j 

1. A HIGH-VOLTAGE FUSE COMPRISING IN COMBINATION: (A) A TUBULAR CASING OF AN ELECTRIC INSULATING MATERIAL; (B) TERMINAL ELEMENTS CLOSING THE ENDS OF SAID CASING; (C) A PULVERULENT ARC-QUENCHING FILLER INSIDE SAID CASING; AND (D) SUBSTANTIALLY ZIG-ZAG SHAPED RIBBON FUSE LINK MEANS INSIDE SAID CASING CONDUCTIVELY INTERCONNECTING SAID PAIR OF TERMINAL ELEMENTS AND SUBMERSED IN SAID ARC-QUENCHING FILLER, SAID FUSE LINK MEANS INCLUDING A PLURALITY OF SERIALLY RELATED FLAT SECTIONS DEFINING PLANES ENCLOSING PREDETERMINED OBTUSE ANGLES, ANY INCREMENT OF THE AREA OF ANY OF SAID PLURALITY OF SECTIONS ENCLOSING SAID PREDETERMINED OBTUSE ANGLE WITH ANY INCREMENT OF THE AREA OF AN ADJACENT OF SAID PLURALITY OF SECTIONS, CONTIGUOUS PAIRS OF SAID SEC- 